<template>
	<!-- 商品分类导航 -->
	<div class="type-nav">
		<div class="container">
			<div @mouseleave="currentIndex = -1">
				<h2 class="all">全部商品分类</h2>
				<div class="sort">
					<!-- 事件委派 -->
					<div class="all-sort-list2" @click="goSearch">
						<div class="item" v-for="(c1,index) in categroyList" :key="c1.categoryId" @mouseenter="changeIndex(index)">
							<h3 :class="{show:currentIndex === index}">
								<a :data-categoryName="c1.categoryName" :data-category1Id="c1.categoryId">{{c1.categoryName}}</a>
							</h3>
							<div class="item-list clearfix">
								<div class="subitem" v-for="(c2,index) in c1.categoryChild" :key="c2.categoryId">
									<dl class="fore">
										<dt>
											<a :data-categoryName="c2.categoryName" :data-category2Id="c2.categoryId">{{c2.categoryName}}</a>
										</dt>
										<dd>
											<em v-for="(c3,index) in c2.categoryChild" :key="c3.categoryId">
												<a :data-categoryName="c3.categoryName" :data-category3Id="c3.categoryId">{{c3.categoryName}}</a>
											</em>
										</dd>
									</dl>
								</div>
							</div>
						</div>
					</div>
				</div>
			</div>
			<nav class="nav">
				<a href="###">服装城</a>
				<a href="###">美妆馆</a>
				<a href="###">尚品汇超市</a>
				<a href="###">全球购</a>
				<a href="###">闪购</a>
				<a href="###">团购</a>
				<a href="###">有趣</a>
				<a href="###">秒杀</a>
			</nav>
		</div>
	</div>
</template>

<script>
	// 按需引入: 把需要的功能引入进来
	import throttle from 'lodash/throttle'
	// vuex 辅助函数mapstate获取仓库数据
	import {
		mapState
	} from 'vuex'
	export default {
		name: '',
		data() {
			return {
				// 索引值存储
				currentIndex: -1
			}
		},
		computed: {
			...mapState({
				categroyList: state => state.home.categroyList
			})
		},
		methods: {
			//h3的鼠标移入事件:用户行为如果过快，会出现浏览器反应不过来的现象
			//节流功能
			changeIndex: throttle(function(index){
				// 修改索引值
				this.currentIndex = index 
			},20),

			// 编程式导航按钮的回调函数
			goSearch(event){
				//点击a标签进行路由跳转：父节点代理的子节点的类型很多 div h3 dd dt em a
				// event可以获取到当前触发事件的节点
				let nodeElement = event.target;
				//给a标签添加自定义属性data-categoryName，保证这个节点带data-categoryName，一定是a标签
      	//可以通过节点的dataset属性获取相应节点的自定义属性，返回的是一个对象KV【自定义属性相关的】
				// categoryName，一定是a标签
				let {categoryname, category1id, category2id, category3id} = nodeElement.dataset
				if(categoryname){
					// 路由跳转的参数
					let location = {name: 'search'}
					let query = {categoryName: categoryname}
					// 区分一级 二级 三级分类的a
					// 一级
					if(category1id){
						query.category1Id = category1id
					// 二级
					}else if(category2id){
						query.category2Id = category2id
					// 三级
					}else{
						query.category3Id = category3id
					}
					// 给locatio动态添加一个属性
					location.query = query;
					this.$router.push(location)
				}
			}
		}
	}
</script>

<style scoped lang="less">
	.type-nav {
		border-bottom: 2px solid #e1251b;

		.container {
			width: 1200px;
			margin: 0 auto;
			display: flex;
			position: relative;

			.all {
				width: 210px;
				height: 45px;
				background-color: #e1251b;
				line-height: 45px;
				text-align: center;
				color: #fff;
				font-size: 14px;
				font-weight: bold;
			}

			.nav {
				a {
					height: 45px;
					margin: 0 22px;
					line-height: 45px;
					font-size: 16px;
					color: #333;
				}
			}

			.sort {
				position: absolute;
				left: 0;
				top: 45px;
				width: 210px;
				height: 461px;
				position: absolute;
				background: #fafafa;
				z-index: 999;

				.all-sort-list2 {
					.item {
						h3 {
							line-height: 30px;
							font-size: 14px;
							font-weight: 400;
							overflow: hidden;
							padding: 0 20px;
							margin: 0;

							a {
								color: #333;
							}

							&.show {
								background: pink;
							}
						}

						.item-list {
							display: none;
							position: absolute;
							width: 734px;
							min-height: 460px;
							background: #f7f7f7;
							left: 210px;
							border: 1px solid #ddd;
							top: 0;
							z-index: 9999 !important;

							.subitem {
								float: left;
								width: 650px;
								padding: 0 4px 0 8px;

								dl {
									border-top: 1px solid #eee;
									padding: 6px 0;
									overflow: hidden;
									zoom: 1;

									&.fore {
										border-top: 0;
									}

									dt {
										float: left;
										width: 54px;
										line-height: 22px;
										text-align: right;
										padding: 3px 6px 0 0;
										font-weight: 700;
									}

									dd {
										float: left;
										width: 415px;
										padding: 3px 0 0;
										overflow: hidden;

										em {
											float: left;
											height: 14px;
											line-height: 14px;
											padding: 0 8px;
											margin-top: 5px;
											border-left: 1px solid #ccc;
										}
									}
								}
							}
						}

						&:hover {
							.item-list {
								display: block;
							}
						}
					}
				}
			}
		}
	}
</style>